Carrier aggregation (ca) configuration during dual-active-protocol stack (daps) handover (ho)

ABSTRACT

Certain aspects of the present disclosure are directed to a method for wireless communication. The method generally includes receiving a message for dual-active-protocol stack (DAPs) handover (HO) from a source network entity to a target network entity, wherein carrier-aggregation (CA) is configured with the source network entity prior to reception of the message for HO, deactivating the CA in response to reception of the message for handover (HO) to activate a single carrier mode with the source network entity, and performing the HO from the source network entity to the target network entity during a HO period, wherein the single carrier mode is maintained with the source network entity during at least a portion of the HO period, and wherein connection with the target network entity is maintained during the at least the portion of the HO period.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.17/061,518, filed Oct. 1, 2020, which claims benefit of and priority toU.S. Provisional Application No. 62/911,013, filed Oct. 4, 2019, whichare hereby assigned to the assignee hereof and hereby expresslyincorporated by reference herein in their entireties as if fully setforth below and for all applicable purposes.

BACKGROUND Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for handover management.

Description of Related Art

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,broadcasts, etc. These wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, etc.). Examples of such multiple-access systems include3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)systems, LTE Advanced (LTE-A) systems, code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system mayinclude a number of base stations (BSs), which are each capable ofsimultaneously supporting communication for multiple communicationdevices, otherwise known as user equipments (UEs). In an LTE or LTE-Anetwork, a set of one or more base stations may define an eNodeB (eNB).In other examples (e.g., in a next generation, a new radio (NR), or 5Gnetwork), a wireless multiple access communication system may include anumber of distributed units (DUs) (e.g., edge units (EUs), edge nodes(ENs), radio heads (RHs), smart radio heads (SRHs), transmissionreception points (TRPs), etc.) in communication with a number of centralunits (CUs) (e.g., central nodes (CNs), access node controllers (ANCs),etc.), where a set of one or more DUs, in communication with a CU, maydefine an access node (e.g., which may be referred to as a BS, 5G NB,next generation NodeB (gNB or gNodeB), transmission reception point(TRP), etc.). A BS or DU may communicate with a set of UEs on downlinkchannels (e.g., for transmissions from a BS or DU to a UE) and uplinkchannels (e.g., for transmissions from a UE to BS or DU).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. NR (e.g., new radio or 5G) is anexample of an emerging telecommunication standard. NR is a set ofenhancements to the LTE mobile standard promulgated by 3GPP. NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink(UL). To these ends, NR supports beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in NR and LTEtechnology. Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes receiving amessage for dual-active-protocol stack (DAPs) handover (HO) from asource network entity to a target network entity, wherein CA isconfigured with the source network entity prior to reception of themessage for HO, deactivating the CA in response to reception of themessage for HO to activate a single carrier mode with the source networkentity, and performing the HO from the source network entity to thetarget network entity during a HO period, wherein the single carriermode is maintained with the source network entity during at least aportion of the HO period, and wherein connection with the target networkentity is maintained during the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes receiving amessage for dual-DAPs HO from a source network entity to a targetnetwork entity, wherein CA is configured for communication with thesource network entity prior to reception of the message for the HO,activating a dormancy CA mode with the source network entity in responseto the reception of the message for HO, and performing the HO from thesource network entity to the target network entity during a HO period,wherein the dormancy CA mode is maintained with the source networkentity during at least a portion of the HO period, and whereinconnection with the target network entity is maintained during the atleast the portion of the HO period.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes receiving amessage for dual-DAPs HO from a source network entity to a targetnetwork entity, wherein CA mode is configured for communication with thesource network entity prior to reception of the message, and performingthe HO from the source network entity to the target network entityduring a HO period, wherein the CA mode with the source network entityis maintained during at least a portion of the HO period, and whereinconnection with the target network entity is maintained during the atleast the portion of the HO period.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes generating amessage for dual-DAPs HO of a UE from a source network entity to atarget network entity, wherein CA is configured for communicationbetween the UE and the source network entity prior to transmission ofthe message for HO, and wherein the message indicates to the UE toactivate a single carrier mode with the source network entity during atleast a portion of the HO period while maintaining connection with thetarget network entity during the at least the portion the HO period, andtransmitting the message for the HO to the UE.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes generating amessage for dual-DAPs HO of a UE from a source network entity to atarget network entity, wherein CA is configured for communicationbetween the UE and the source network entity prior to transmission ofthe message for the HO, wherein the message indicates to the UE toactivate a dormancy CA mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion of the HO period,and transmitting the message to the UE.

Certain aspects of the present disclosure are directed to a method forwireless communication. The method generally includes generating amessage for dual-DAPs HO of a UE from a source network entity to atarget network entity, wherein CA mode is configured for communicationbetween the UE and the source network entity prior to transmission ofthe message for HO, and wherein the message indicate for the UE tomaintain the CA mode with the source network entity during at least aportion of a HO period while maintaining connection with the targetnetwork entity during the at least the portion of the HO period, andtransmitting the message for HO to the UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to receive a message for DAPs HOfrom a source network entity to a target network entity, wherein CA isconfigured with the source network entity prior to reception of themessage for HO, deactivate the CA in response to reception of themessage for HO to activate a single carrier mode with the source networkentity, and perform the HO from the source network entity to the targetnetwork entity during a HO period, wherein the single carrier mode ismaintained with the source network entity during at least a portion ofthe HO period, and wherein connection with the target network entity ismaintained during the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to receive a message for dual-DAPsHO from a source network entity to a target network entity, wherein CAis configured for communication with the source network entity prior toreception of the message for the HO, activate a dormancy CA mode withthe source network entity in response to the reception of the messagefor HO, and perform the HO from the source network entity to the targetnetwork entity during a HO period, wherein the dormancy CA mode ismaintained with the source network entity during at least a portion ofthe HO period, and wherein connection with the target network entity ismaintained during the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to receive a message for dual-DAPsHO from a source network entity to a target network entity, wherein CAmode is configured for communication with the source network entityprior to reception of the message, and perform the HO from the sourcenetwork entity to the target network entity during a HO period, whereinthe CA mode with the source network entity is maintained during at leasta portion of the HO period, and wherein connection with the targetnetwork entity is maintained during the at least the portion of the HOperiod.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to generate a message for dual-DAPsHO of a UE from a source network entity to a target network entity,wherein CA is configured for communication between the UE and the sourcenetwork entity prior to transmission of the message for HO, and whereinthe message indicates to the UE to activate a single carrier mode withthe source network entity during at least a portion of the HO periodwhile maintaining connection with the target network entity during theat least the portion the HO period, and transmit the message for the HOto the UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to generate a message for dual-DAPsHO of a UE from a source network entity to a target network entity,wherein CA is configured for communication between the UE and the sourcenetwork entity prior to transmission of the message for the HO, whereinthe message indicates to the UE to activate a dormancy CA mode with thesource network entity during at least a portion of a HO period whilemaintaining connection with the target network entity during the atleast the portion of the HO period, and transmit the message to the UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes a memoryand one or more processors coupled to the memory, the memory and the oneor more processors being configured to generate a message for dual-DAPsHO of a UE from a source network entity to a target network entity,wherein CA mode is configured for communication between the UE and thesource network entity prior to transmission of the message for HO, andwherein the message indicate for the UE to maintain the CA mode with thesource network entity during at least a portion of a HO period whilemaintaining connection with the target network entity during the atleast the portion of the HO period, and transmit the message for HO tothe UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forreceiving a message for DAPs HO from a source network entity to a targetnetwork entity, wherein CA is configured with the source network entityprior to reception of the message for HO, means for deactivating the CAin response to reception of the message for HO to activate a singlecarrier mode with the source network entity, and means for performingthe HO from the source network entity to the target network entityduring a HO period, wherein the single carrier mode is maintained withthe source network entity during at least a portion of the HO period,and wherein connection with the target network entity is maintainedduring the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forreceiving a message for dual-DAPs HO from a source network entity to atarget network entity, wherein CA is configured for communication withthe source network entity prior to reception of the message for the HO,means for activating a dormancy CA mode with the source network entityin response to the reception of the message for HO, and means forperforming the HO from the source network entity to the target networkentity during a HO period, wherein the dormancy CA mode is maintainedwith the source network entity during at least a portion of the HOperiod, and wherein connection with the target network entity ismaintained during the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forreceiving a message for dual-DAPs HO from a source network entity to atarget network entity, wherein CA mode is configured for communicationwith the source network entity prior to reception of the message, andmeans for performing the HO from the source network entity to the targetnetwork entity during a HO period, wherein the CA mode with the sourcenetwork entity is maintained during at least a portion of the HO period,and wherein connection with the target network entity is maintainedduring the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forgenerating a message for dual-DAPs HO of a UE from a source networkentity to a target network entity, wherein CA is configured forcommunication between the UE and the source network entity prior totransmission of the message for HO, and wherein the message indicates tothe UE to activate a single carrier mode with the source network entityduring at least a portion of the HO period while maintaining connectionwith the target network entity during the at least the portion the HOperiod, and means for transmitting the message for the HO to the UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forgenerating a message for dual-DAPs HO of a UE from a source networkentity to a target network entity, wherein CA is configured forcommunication between the UE and the source network entity prior totransmission of the message for the HO, wherein the message indicates tothe UE to activate a dormancy CA mode with the source network entityduring at least a portion of a HO period while maintaining connectionwith the target network entity during the at least the portion of the HOperiod, and means for transmitting the message to the UE.

Certain aspects of the present disclosure are directed to an apparatusfor wireless communication. The apparatus generally includes means forgenerating a message for dual-DAPs HO of a UE from a source networkentity to a target network entity, wherein CA mode is configured forcommunication between the UE and the source network entity prior totransmission of the message for HO, and wherein the message indicate forthe UE to maintain the CA mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion of the HO period,and means for transmitting the message for HO to the UE.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to receive a message for DAPs HO from a source network entityto a target network entity, wherein CA is configured with the sourcenetwork entity prior to reception of the message for HO, deactivate theCA in response to reception of the message for HO to activate a singlecarrier mode with the source network entity, and perform the HO from thesource network entity to the target network entity during a HO period,wherein the single carrier mode is maintained with the source networkentity during at least a portion of the HO period, and whereinconnection with the target network entity is maintained during the atleast the portion of the HO period.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to receive a message for dual-DAPs HO from a source networkentity to a target network entity, wherein CA is configured forcommunication with the source network entity prior to reception of themessage for the HO, activate a dormancy CA mode with the source networkentity in response to the reception of the message for HO, andperforming the HO from the source network entity to the target networkentity during a HO period, wherein the dormancy CA mode is maintainedwith the source network entity during at least a portion of the HOperiod, and wherein connection with the target network entity ismaintained during the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to receive a message for dual-DAPs HO from a source networkentity to a target network entity, wherein CA mode is configured forcommunication with the source network entity prior to reception of themessage, and perform the HO from the source network entity to the targetnetwork entity during a HO period, wherein the CA mode with the sourcenetwork entity is maintained during at least a portion of the HO period,and wherein connection with the target network entity is maintainedduring the at least the portion of the HO period.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to generate a message for dual-DAPs HO of a UE from a sourcenetwork entity to a target network entity, wherein CA is configured forcommunication between the UE and the source network entity prior totransmission of the message for HO, and wherein the message indicates tothe UE to activate a single carrier mode with the source network entityduring at least a portion of the HO period while maintaining connectionwith the target network entity during the at least the portion the HOperiod, and transmit the message for the HO to the UE.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to generate a message for dual-DAPs HO of a UE from a sourcenetwork entity to a target network entity, wherein CA is configured forcommunication between the UE and the source network entity prior totransmission of the message for the HO, wherein the message indicates tothe UE to activate a dormancy CA mode with the source network entityduring at least a portion of a HO period while maintaining connectionwith the target network entity during the at least the portion of the HOperiod, and transmit the message to the UE.

Certain aspects of the present disclosure are directed to acomputer-readable medium having instructions stored thereon to cause aprocessor to generate a message for dual-DAPs HO of a UE from a sourcenetwork entity to a target network entity, wherein CA mode is configuredfor communication between the UE and the source network entity prior totransmission of the message for HO, and wherein the message indicate forthe UE to maintain the CA mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion of the HO period,and transmit the message for HO to the UE.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe appended drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the drawings. It is to be noted, however, thatthe appended drawings illustrate only certain typical aspects of thisdisclosure and are therefore not to be considered limiting of its scope,for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram illustrating an example architecture of adistributed radio access network (RAN), in accordance with certainaspects of the present disclosure.

FIG. 3 is a block diagram showing examples for implementing acommunication protocol stack in the example RAN architecture, inaccordance with certain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample base station (BS) and user equipment (UE), in accordance withcertain aspects of the present disclosure.

FIG. 5 illustrates an example system architecture for interworkingbetween a 5G System (5GS) and an evolved universal mobiletelecommunication system network (E-UTRAN) system, in accordance withcertain aspects of the present disclosure.

FIG. 6 illustrates an example of a frame format for a telecommunicationsystem, in accordance with certain aspects of the present disclosure.

FIG. 7 is a call flow for make-before-break (MBB) handover (HO), inaccordance with certain aspects of the present disclosure.

FIG. 8 is a flow diagram illustrating example operations for wirelesscommunication by a UE, in accordance with certain aspects of the presentdisclosure.

FIG. 9 is a flow diagram illustrating example operations for wirelesscommunication by a BS, in accordance with certain aspects of the presentdisclosure.

FIG. 10 is a timing diagram illustrating a connection mode of a sourcecell and a target cell during MBB HO, in accordance with certain aspectsof the present disclosure.

FIG. 11 is a flow diagram illustrating example operations for wirelesscommunication by a UE, in accordance with certain aspects of the presentdisclosure.

FIG. 12 is a flow diagram illustrating example operations for wirelesscommunication by a BS, in accordance with certain aspects of the presentdisclosure.

FIG. 13 is a timing diagram illustrating a connection mode of a sourcecell and a target cell during MBB HO, in accordance with certain aspectsof the present disclosure.

FIG. 14 is a flow diagram illustrating example operations for wirelesscommunication by a UE, in accordance with certain aspects of the presentdisclosure.

FIG. 15 is a flow diagram illustrating example operations for wirelesscommunication by a BS, in accordance with certain aspects of the presentdisclosure.

FIG. 16 is a timing diagram illustrating a connection mode of a sourcecell and a target cell during MBB HO, in accordance with certain aspectsof the present disclosure.

FIG. 17 illustrates a communications device that may include variouscomponents configured to perform operations for the techniques disclosedherein.

FIG. 18 illustrates a communications device that may include variouscomponents configured to perform operations for the techniques disclosedherein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in some other examples. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition to,or other than, the various aspects of the disclosure set forth herein.It should be understood that any aspect of the disclosure disclosedherein may be embodied by one or more elements of a claim. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects.

The techniques described herein may be used for various wirelesscommunication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA,SC-FDMA and other networks. The terms “network” and “system” are oftenused interchangeably. A CDMA network may implement a radio technologysuch as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRAincludes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA network may implement a radio technology such as NR(e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRAand E-UTRA are part of Universal Mobile Telecommunication System (UMTS).

New Radio (NR) is an emerging wireless communications technology underdevelopment in conjunction with the 5G Technology Forum (5GTF). 3GPPLong Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTSthat use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described indocuments from an organization named “3rd Generation PartnershipProject” (3GPP). cdma2000 and UMB are described in documents from anorganization named “3rd Generation Partnership Project 2” (3GPP2). Thetechniques described herein may be used for the wireless networks andradio technologies mentioned above as well as other wireless networksand radio technologies. For clarity, while aspects may be describedherein using terminology commonly associated with 3G and/or 4G wirelesstechnologies, aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

New radio (NR) access (e.g., 5G technology) may support various wirelesscommunication services, such as enhanced mobile broadband (eMBB)targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW)targeting high carrier frequency (e.g., 25 GHz or beyond), massivemachine type communications MTC (mMTC) targeting non-backward compatibleMTC techniques, and/or mission critical targeting ultra-reliablelow-latency communications (URLLC). These services may include latencyand reliability requirements. These services may also have differenttransmission time intervals (TTI) to meet respective quality of service(QoS) requirements. In addition, these services may co-exist in the samesubframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 inwhich aspects of the present disclosure may be performed. For example,the wireless communication network 100 may be a New Radio (NR) or 5Gnetwork.

As illustrated in FIG. 1 , the wireless communication network 100 mayinclude a number of base stations (BSs) 110 and other network entities.A BS may be a station that communicates with user equipments (UEs). EachBS 110 may provide communication coverage for a particular geographicarea. In 3GPP, the term “cell” can refer to a coverage area of a Node B(NB) and/or a NB subsystem serving this coverage area, depending on thecontext in which the term is used. In NR systems, the term “cell” andnext generation NodeB (gNB or gNodeB), NR BS, 5G NB, access point (AP),or transmission reception point (TRP) may be interchangeable. In someexamples, a cell may not necessarily be stationary, and the geographicarea of the cell may move according to the location of a mobile BS. Insome examples, the base stations may be interconnected to one anotherand/or to one or more other base stations or network nodes (not shown)in wireless communication network 100 through various types of backhaulinterfaces, such as a direct physical connection, a wireless connection,a virtual network, or the like using any suitable transport network.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a subcarrier, afrequency channel, a tone, a subband, etc. Each frequency may support asingle RAT in a given geographic area in order to avoid interferencebetween wireless networks of different RATs. In some cases, NR or 5G RATnetworks may be deployed.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or other types of cells. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having an association with the femto cell(e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in thehome, etc.). A BS for a macro cell may be referred to as a macro BS. ABS for a pico cell may be referred to as a pico BS. A BS for a femtocell may be referred to as a femto BS or a home BS. In the example shownin FIG. 1 , the BSs 110 a, 110 b and 110 c may be macro BSs for themacro cells 102 a, 102 b and 102 c, respectively. The BS 110 x may be apico BS for a pico cell 102 x. The BSs 110 y and 110 z may be femto BSsfor the femto cells 102 y and 102 z, respectively. A BS may support oneor multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. Arelay station is a station that receives a transmission of data and/orother information from an upstream station (e.g., a BS or a UE) andsends a transmission of the data and/or other information to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that relays transmissions for other UEs. In the example shown in FIG.1 , a relay station 110 r may communicate with the BS 110 a and a UE 120r in order to facilitate communication between the BS 110 a and the UE120 r. A relay station may also be referred to as a relay BS, a relay,etc.

Wireless communication network 100 may be a heterogeneous network thatincludes BSs of different types, e.g., macro BS, pico BS, femto BS,relays, etc. These different types of BSs may have different transmitpower levels, different coverage areas, and different impact oninterference in the wireless communication network 100. For example,macro BS may have a high transmit power level (e.g., 20 Watts) whereaspico BS, femto BS, and relays may have a lower transmit power level(e.g., 1 Watt).

Wireless communication network 100 may support synchronous orasynchronous operation. For synchronous operation, the BSs may havesimilar frame timing, and transmissions from different BSs may beapproximately aligned in time. For asynchronous operation, the BSs mayhave different frame timing, and transmissions from different BSs maynot be aligned in time. The techniques described herein may be used forboth synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and providecoordination and control for these BSs. The network controller 130 maycommunicate with the BSs 110 via a backhaul. The BSs 110 may alsocommunicate with one another (e.g., directly or indirectly) via wirelessor wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless communication network 100, and each UE may be stationary ormobile. A UE may also be referred to as a mobile station, a terminal, anaccess terminal, a subscriber unit, a station, a Customer PremisesEquipment (CPE), a cellular phone, a smart phone, a personal digitalassistant (PDA), a wireless modem, a wireless communication device, ahandheld device, a laptop computer, a cordless phone, a wireless localloop (WLL) station, a tablet computer, a camera, a gaming device, anetbook, a smartbook, an ultrabook, an appliance, a medical device ormedical equipment, a biometric sensor/device, a wearable device such asa smart watch, smart clothing, smart glasses, a smart wrist band, smartjewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainmentdevice (e.g., a music device, a video device, a satellite radio, etc.),a vehicular component or sensor, a smart meter/sensor, industrialmanufacturing equipment, a global positioning system device, or anyother suitable device that is configured to communicate via a wirelessor wired medium. Some UEs may be considered machine-type communication(MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include,for example, robots, drones, remote devices, sensors, meters, monitors,location tags, etc., that may communicate with a BS, another device(e.g., remote device), or some other entity. A wireless node mayprovide, for example, connectivity for or to a network (e.g., a widearea network such as Internet or a cellular network) via a wired orwireless communication link. Some UEs may be consideredInternet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT)devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, etc. Each subcarriermay be modulated with data. In general, modulation symbols are sent inthe frequency domain with OFDM and in the time domain with SC-FDM. Thespacing between adjacent subcarriers may be fixed, and the total numberof subcarriers (K) may be dependent on the system bandwidth. Forexample, the spacing of the subcarriers may be 15 kHz and the minimumresource allocation (called a “resource block” (RB)) may be 12subcarriers (or 180 kHz). Consequently, the nominal Fast FourierTransfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 forsystem bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz),respectively. The system bandwidth may also be partitioned intosubbands. For example, a subband may cover 1.8 MHz (i.e., 6 resourceblocks), and there may be 1, 2, 4, 8, or 16 subbands for systembandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR. NR may utilizeOFDM with a CP on the uplink and downlink and include support forhalf-duplex operation using TDD. Beamforming may be supported and beamdirection may be dynamically configured. MIMO transmissions withprecoding may also be supported. MIMO configurations in the DL maysupport up to 8 transmit antennas with multi-layer DL transmissions upto 8 streams and up to 2 streams per UE. Multi-layer transmissions withup to 2 streams per UE may be supported. Aggregation of multiple cellsmay be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled. Ascheduling entity (e.g., a BS) allocates resources for communicationamong some or all devices and equipment within its service area or cell.The scheduling entity may be responsible for scheduling, assigning,reconfiguring, and releasing resources for one or more subordinateentities. That is, for scheduled communication, subordinate entitiesutilize resources allocated by the scheduling entity. Base stations arenot the only entities that may function as a scheduling entity. In someexamples, a UE may function as a scheduling entity and may scheduleresources for one or more subordinate entities (e.g., one or more otherUEs), and the other UEs may utilize the resources scheduled by the UEfor wireless communication. In some examples, a UE may function as ascheduling entity in a peer-to-peer (P2P) network, and/or in a meshnetwork. In a mesh network example, UEs may communicate directly withone another in addition to communicating with a scheduling entity.

In FIG. 1 , a solid line with double arrows indicates desiredtransmissions between a UE and a serving BS, which is a BS designated toserve the UE on the downlink and/or uplink. A finely dashed line withdouble arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates an example architecture of a distributed Radio AccessNetwork (RAN) 200, which may be implemented in the wirelesscommunication network 100 illustrated in FIG. 1 . As shown in FIG. 2 ,the distributed RAN includes Core Network (CN) 202 and Access Node 208.

The CN 202 may host core network functions. CN 202 may be centrallydeployed. CN 202 functionality may be offloaded (e.g., to advancedwireless services (AWS)), in an effort to handle peak capacity. The CN202 may include the Access and Mobility Management Function (AMF) 204and User Plane Function (UPF) 206. The AMF 204 and UPF 206 may performone or more of the core network functions.

The AN 208 may communicate with the CN 202 (e.g., via a backhaulinterface). The AN 208 may communicate with the AMF 204 via an N2 (e.g.,NG-C) interface. The AN 208 may communicate with the UPF 208 via an N3(e.g., NG-U) interface. The AN 208 may include a central unit-controlplane (CU-CP) 210, one or more central unit-user plane (CU-UPs) 212, oneor more distributed units (DUs) 214-218, and one or more Antenna/RemoteRadio Units (AU/RRUs) 220-224. The CUs and DUs may also be referred toas gNB-CU and gNB-DU, respectively. One or more components of the AN 208may be implemented in a gNB 226. The AN 208 may communicate with one ormore neighboring gNB s.

The CU-CP 210 may be connected to one or more of the DUs 214-218. TheCU-CP 210 and DUs 214-218 may be connected via a F1-C interface. Asshown in FIG. 2 , the CU-CP 210 may be connected to multiple DUs, butthe DUs may be connected to only one CU-CP. Although FIG. 2 onlyillustrates one CU-UP 212, the AN 208 may include multiple CU-UPs. TheCU-CP 210 selects the appropriate CU-UP(s) for requested services (e.g.,for a UE).

The CU-UP(s) 212 may be connected to the CU-CP 210. For example, theDU-UP(s) 212 and the CU-CP 210 may be connected via an E1 interface. TheCU-CP(s) 212 may connected to one or more of the DUs 214-218. TheCU-UP(s) 212 and DUs 214-218 may be connected via a F1-U interface. Asshown in FIG. 2 , the CU-CP 210 may be connected to multiple CU-UPs, butthe CU-UPs may be connected to only one CU-CP.

A DU, such as DUs 214, 216, and/or 218, may host one or more TRP(s)(transmit/receive points, which may include an Edge Node (EN), an EdgeUnit (EU), a Radio Head (RH), a Smart Radio Head (SRH), or the like). ADU may be located at edges of the network with radio frequency (RF)functionality. A DU may be connected to multiple CU-UPs that areconnected to (e.g., under the control of) the same CU-CP (e.g., for RANsharing, radio as a service (RaaS), and service specific deployments).DUs may be configured to individually (e.g., dynamic selection) orjointly (e.g., joint transmission) serve traffic to a UE. Each DU214-216 may be connected with one of AU/RRUs 220-224. The DU may beconnected to an AU/RRU via each of the F1-C and F1-U interfaces.

The CU-CP 210 may be connected to multiple DU(s) that are connected to(e.g., under control of) the same CU-UP 212. Connectivity between aCU-UP 212 and a DU may be established by the CU-CP 210. For example, theconnectivity between the CU-UP 212 and a DU may be established usingBearer Context Management functions. Data forwarding between CU-UP(s)212 may be via a Xn-U interface.

The distributed RAN 200 may support fronthauling solutions acrossdifferent deployment types. For example, the RAN 200 architecture may bebased on transmit network capabilities (e.g., bandwidth, latency, and/orjitter). The distributed RAN 200 may share features and/or componentswith LTE. For example, AN 208 may support dual connectivity with NR andmay share a common fronthaul for LTE and NR. The distributed RAN 200 mayenable cooperation between and among DUs 214-218, for example, via theCU-CP 212. An inter-DU interface may not be used.

Logical functions may be dynamically distributed in the distributed RAN200. As will be described in more detail with reference to FIG. 3 , theRadio Resource Control (RRC) layer, Packet Data Convergence Protocol(PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control(MAC) layer, Physical (PHY) layers, and/or Radio Frequency (RF) layersmay be adaptably placed, in the N AN and/or UE.

FIG. 3 illustrates a diagram showing examples for implementing acommunications protocol stack 300 in a RAN (e.g., such as the RAN 200),according to aspects of the present disclosure. The illustratedcommunications protocol stack 300 may be implemented by devicesoperating in a wireless communication system, such as a 5G NR system(e.g., the wireless communication network 100). In various examples, thelayers of the protocol stack 300 may be implemented as separate modulesof software, portions of a processor or ASIC, portions of non-collocateddevices connected by a communications link, or various combinationsthereof. Collocated and non-collocated implementations may be used, forexample, in a protocol stack for a network access device or a UE. Asshown in FIG. 3 , the system may support various services over one ormore protocols. One or more protocol layers of the protocol stack 300may be implemented by the AN and/or the UE.

As shown in FIG. 3 , the protocol stack 300 is split in the AN (e.g., AN208 in FIG. 2 ). The RRC layer 305, PDCP layer 310, RLC layer 315, MAClayer 320, PHY layer 325, and RF layer 330 may be implemented by the AN.For example, the CU-CP (e.g., CU-CP 210 in FIG. 2 ) and the CU-UP e.g.,CU-UP 212 in FIG. 2 ) each may implement the RRC layer 305 and the PDCPlayer 310. A DU (e.g., DUs 214-218 in FIG. 2 ) may implement the RLClayer 315 and MAC layer 320. The AU/RRU (e.g., AU/RRUs 220-224 in FIG. 2) may implement the PHY layer(s) 325 and the RF layer(s) 330. The PHYlayers 325 may include a high PHY layer and a low PHY layer.

The UE may implement the entire protocol stack 300 (e.g., the RRC layer305, the PDCP layer 310, the RLC layer 315, the MAC layer 320, the PHYlayer(s) 325, and the RF layer(s) 330).

FIG. 4 illustrates example components of BS 110 and UE 120 (as depictedin FIG. 1 ), which may be used to implement aspects of the presentdisclosure. For example, antennas 452, processors 466, 458, 464, and/orcontroller/processor 480 of the UE 120 and/or antennas 434, processors420, 430, 438, and/or controller/processor 440 of the BS 110 may be usedto perform the various techniques and methods described herein.

At the BS 110, a transmit processor 420 may receive data from a datasource 412 and control information from a controller/processor 440. Thecontrol information may be for the physical broadcast channel (PBCH),physical control format indicator channel (PCFICH), physical hybrid ARQindicator channel (PHICH), physical downlink control channel (PDCCH),group common PDCCH (GC PDCCH), etc. The data may be for the physicaldownlink shared channel (PDSCH), etc. The processor 420 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The processor 420 mayalso generate reference symbols, e.g., for the primary synchronizationsignal (PSS), secondary synchronization signal (SSS), and cell-specificreference signal (CRS). A transmit (TX) multiple-input multiple-output(MIMO) processor 430 may perform spatial processing (e.g., precoding) onthe data symbols, the control symbols, and/or the reference symbols, ifapplicable, and may provide output symbol streams to the modulators(MODs) 432 a through 432 t. Each modulator 432 may process a respectiveoutput symbol stream (e.g., for OFDM, etc.) to obtain an output samplestream. Each modulator may further process (e.g., convert to analog,amplify, filter, and upconvert) the output sample stream to obtain adownlink signal. Downlink signals from modulators 432 a through 432 tmay be transmitted via the antennas 434 a through 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) in transceivers 454 a through 454 r,respectively. Each demodulator 454 may condition (e.g., filter, amplify,downconvert, and digitize) a respective received signal to obtain inputsamples. Each demodulator may further process the input samples (e.g.,for OFDM, etc.) to obtain received symbols. A MIMO detector 456 mayobtain received symbols from all the demodulators 454 a through 454 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 458 may process (e.g.,demodulate, deinterleave, and decode) the detected symbols, providedecoded data for the UE 120 to a data sink 460, and provide decodedcontrol information to a controller/processor 480.

On the uplink, at UE 120, a transmit processor 464 may receive andprocess data (e.g., for the physical uplink shared channel (PUSCH)) froma data source 462 and control information (e.g., for the physical uplinkcontrol channel (PUCCH) from the controller/processor 480. The transmitprocessor 464 may also generate reference symbols for a reference signal(e.g., for the sounding reference signal (SRS)). The symbols from thetransmit processor 464 may be precoded by a TX MIMO processor 466 ifapplicable, further processed by the demodulators in transceivers 454 athrough 454 r (e.g., for SC-FDM, etc.), and transmitted to the basestation 110. At the BS 110, the uplink signals from the UE 120 may bereceived by the antennas 434, processed by the modulators 432, detectedby a MIMO detector 436 if applicable, and further processed by a receiveprocessor 438 to obtain decoded data and control information sent by theUE 120. The receive processor 438 may provide the decoded data to a datasink 439 and the decoded control information to the controller/processor440.

The controllers/processors 440 and 480 may direct the operation at theBS 110 and the UE 120, respectively. The processor 440 and/or otherprocessors and modules at the BS 110 may perform or direct the executionof processes for the techniques described herein. The memories 442 and482 may store data and program codes for BS 110 and UE 120,respectively. A scheduler 444 may schedule UEs for data transmission onthe downlink and/or uplink.

FIG. 5 illustrates an example system architecture 500 for interworkingbetween 5GS (e.g., such as the distributed RAN 200) and E-UTRAN-EPC, inaccordance with certain aspects of the present disclosure. As shown inFIG. 5 , the UE 502 may be served by separate RANs 504A and 504Bcontrolled by separate core networks 506A and 506B, where the RAN 504Aprovides E-UTRA services and RAN 504B provides 5G NR services. The UEmay operate under only one RAN/CN or both RANs/CNs at a time.

In LTE, the basic transmission time interval (TTI) or packet duration isthe 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI isreferred to as a slot. A subframe contains a variable number of slots(e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing.The NR RB is 12 consecutive frequency subcarriers. NR may support a basesubcarrier spacing of 15 KHz and other subcarrier spacing may be definedwith respect to the base subcarrier spacing, for example, 30 kHz, 60kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with thesubcarrier spacing. The CP length also depends on the subcarrierspacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 ms) and may be partitioned into 10subframes, each of 1 ms, with indices of 0 through 9. Each subframe mayinclude a variable number of slots depending on the subcarrier spacing.Each slot may include a variable number of symbol periods (e.g., 7 or 14symbols) depending on the subcarrier spacing. The symbol periods in eachslot may be assigned indices. A mini-slot, which may be referred to as asub-slot structure, refers to a transmit time interval having a durationless than a slot (e.g., 2, 3, or 4 symbols).

Each symbol in a slot may indicate a link direction (e.g., DL, UL, orflexible) for data transmission and the link direction for each subframemay be dynamically switched. The link directions may be based on theslot format. Each slot may include DL/UL data as well as DL/UL controlinformation.

In NR, a synchronization signal (SS) block is transmitted. The SS blockincludes a PSS, a SSS, and a two symbol PBCH. The SS block can betransmitted in a fixed slot location, such as the symbols 0-3 as shownin FIG. 6 . The PSS and SSS may be used by UEs for cell search andacquisition. The PSS may provide half-frame timing, the SS may providethe CP length and frame timing. The PSS and SSS may provide the cellidentity. The PBCH carries some basic system information, such asdownlink system bandwidth, timing information within radio frame, SSburst set periodicity, system frame number, etc. The SS blocks may beorganized into SS bursts to support beam sweeping. Further systeminformation such as, remaining minimum system information (RMSI), systeminformation blocks (SIBs), other system information (OSI) can betransmitted on a physical downlink shared channel (PDSCH) in certainsubframes. The SS block can be transmitted up to sixty-four times, forexample, with up to sixty-four different beam directions for mmW. The upto sixty-four transmissions of the SS block are referred to as the SSburst set. SS blocks in an SS burst set are transmitted in the samefrequency region, while SS blocks in different SS bursts sets can betransmitted at different frequency locations.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

A UE may operate in various radio resource configurations, including aconfiguration associated with transmitting pilots using a dedicated setof resources (e.g., a radio resource control (RRC) dedicated state,etc.) or a configuration associated with transmitting pilots using acommon set of resources (e.g., an RRC common state, etc.). Whenoperating in the RRC dedicated state, the UE may select a dedicated setof resources for transmitting a pilot signal to a network. Whenoperating in the RRC common state, the UE may select a common set ofresources for transmitting a pilot signal to the network. In eithercase, a pilot signal transmitted by the UE may be received by one ormore network access devices, such as an AN, or a DU, or portionsthereof. Each receiving network access device may be configured toreceive and measure pilot signals transmitted on the common set ofresources, and also receive and measure pilot signals transmitted ondedicated sets of resources allocated to the UEs for which the networkaccess device is a member of a monitoring set of network access devicesfor the UE. One or more of the receiving network access devices, or a CUto which receiving network access device(s) transmit the measurements ofthe pilot signals, may use the measurements to identify serving cellsfor the UEs, or to initiate a change of serving cell for one or more ofthe UEs.

Example Carrier Aggregation Configuration During Dual-Active-ProtocolStack (DAPS) Handover (HO)

One of the goals in mobility enhancement is to accomplish little to nointerruption time during handover of a user-equipment (UE) betweencells. In some cases, interruption may be reduced by maintaining thesource link during target link establishment using a make-before-break(MBB) handover (HO) technique. During the MBB HO, the UE may be expectedto maintain connectivity with the source and target base stations (e.g.,gNBs). This simultaneous connectivity to both the source and target basestations may involve certain beams/panels at the UE being used fortransmission and reception from the source and target cells. Thus, theUE may maintain two separate protocol stacks during this HO. Therefore,the MBB HO may also be known as a dual-active-protocol stack (DAPs) HO.In some cases, prior to sending DAPs HO command to the UE, the sourcecell may be in CA mode and the target cell may also need to beconfigured in CA mode. Certain aspects of the present disclosure aregenerally directed to techniques for CA configuration during DAPs HO.

FIG. 7 is a call flow for MBB HO, in accordance with certain aspects ofthe present disclosure. As illustrated, upon an event trigger, the UE702 may transmit, at step 1, a measurement report to a sourcegNB-distributed unit (DU) 704, as well as the gNB-central unit (CU) 708.Based on the measurement report, the CU 708 may make a MBB HO decision.At step 2, a UE context setup request/response procedure with the targetgNB-DU 706 is performed, as illustrated. At step 3, a radio resourcecontrol (RRC) reconfiguration message may be sent to the source-gNB-DU704 and the UE 702. The RRC reconfiguration message may configure theMBB HO such that the UE maintains connection with both the target andsource gNB-DUs during a HO period. The RRC reconfiguration message mayalso configure a type of connection to be maintained during the HOperiod (e.g., single carrier, CA, or a dormancy CA) with the target andsource gNB-DUs, as described in more detail herein. The type ofconnection to be maintained may be determined by the gNB-CU during theMBB HO decision.

At step 4 a, data transmission and reception may continue with thesource gNB-DU 704 using the user-plane function 710 while, at step 4 b,a connection to the target gNB is established (e.g., synchronization andradio access channel (RACH) signaling is performed). Once the RRCconnection reconfiguration is completed, the UE sends, at step 5, a RRCconnection reconfiguration complete message to the target gNB-DU 706 aswell as the gNB-CU 708. The gNB-CU then makes a source gNB-DU connectionrelease decision, and at step 6, UE context modificationrequest/response with the source gNB-DU 704 is performed. At step 7, anRRC reconfiguration message is sent to the target gNB-DU 706 and the UE,the RRC reconfiguration message indicating to the UE to release theconnection from the source gNB-DU 704. The UE then releases theconnection from the source gNB-DU 704 and transmits a RRCreconfiguration complete message to the target gNB-DU 706 and the gNB-CU708, in response to which UE context release from the source gNB-DU 704is performed at step 9.

As illustrated, during the HO period 720 (or at least a portionthereof), the UE maintains connection with both the source and targetgNB-DUs, reducing any interruption to service experienced by a userduring HO. In other words, the UE maintains simultaneous connectivitywith the source and target gNB-DUs during at least a portion of the HOperiod 720. For example, both downlink (DL) and uplink (UL) signalingbetween the UE and the source gNB-DU 704 may be supported simultaneouslywith RACH signaling with the target gNB-DU 706. Moreover, DL and ULsignaling with the source gNB-DU 704 may be supported by the UEsimultaneously with DL and UL signaling with the target gNB-DU 706.

As described herein, CA may be implemented with the target gNB-DU andthe source gNB-DU. However, supporting CA with both the target gNB-DUand the source gNB-DU may be difficult (or not possible) for certainUEs. Certain aspects of the present disclosure are directed totechniques for handing MBB HO with CA.

FIG. 8 is a flow diagram illustrating example operations 800 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 800 may be performed, for example, byUE (e.g., such as a UE 120 in the wireless communication network 100).

Operations 800 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 480 of FIG.4 ). Further, the transmission and reception of signals by the UE inoperations 800 may be enabled, for example, by one or more antennas(e.g., antennas 452 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the UE may be implemented via a businterface of one or more processors (e.g., processor 480) obtainingand/or outputting signals.

The operations 800 may begin, at block 802, by the UE receiving amessage for DAPs HO (e.g., the RRC reconfiguration message at step 3 inFIG. 7 ) from a source network entity (e.g., the source gNB-DU 704) to atarget network entity (e.g., the target gNB-DU 706), wherein CA isconfigured with the source network entity prior to reception of themessage for HO. At block 804, the UE may deactivate the CA in responseto reception of the message for HO to activate a single carrier modewith the source network entity, and at block 806, perform the HO fromthe source network entity to the target network entity during a HOperiod (e.g., HO period 720). In certain aspects, the single carriermode may be maintained with the source network entity during at least aportion of the HO period, and connection with the target network entitymay be maintained during the at least the portion of the HO period. Insome cases, the message for HO may include an indication to deactivatethe CA mode with the source network entity, as described herein.

FIG. 9 is a flow diagram illustrating example operations 900 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 900 may be performed, for example, bya BS (e.g., such as a BS 110 in the wireless communication network 100,or the gNB-CU in FIG. 7 ).

Operations 900 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 440 of FIG.4 ). Further, the transmission and reception of signals by the BS inoperations 900 may be enabled, for example, by one or more antennas(e.g., antennas 434 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the BS may be implemented via a businterface of one or more processors (e.g., processor 440) obtainingand/or outputting signals.

The operations 900 may begin, at block 902, by the BS generating amessage for DAPs HO of a UE from a source network entity to a targetnetwork entity, where CA is configured for communication between the UEand the source network entity prior to transmission of the message forHO. In certain aspects, the message may indicate to the UE to activate asingle carrier mode with the source network entity during a HO periodwhile maintaining connection with the target network entity during atleast a portion of the HO period. At block 904, the BS transmits themessage for the HO to the UE.

FIG. 10 is a timing diagram illustrating a connection mode of a sourcecell (e.g., source network entity) and a target cell (e.g., targetnetwork entity) during MBB HO, in accordance with certain aspects of thepresent disclosure. During the time period 1002, the UE may be insimultaneous connection with both the source and target cells. Asillustrated, the CA mode may be fully deactivated on the source cell.The UE may configure CA mode with the target cell after UE connects tothe target cell, or may configure single carrier (e.g., single CC) modewith the target cell after connection. In certain aspects, the sourcecell may send a CA reconfiguration message to the UE alongside the DAPsHO command (e.g., RRC reconfiguration message at step 3 of FIG. 7 ) sothat the CA is deactivated. As illustrated, during the HO period 720 (orat least a portion thereof), a single carrier mode may be active for thetarget cell.

FIG. 11 is a flow diagram illustrating example operations 1100 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 1100 may be performed, for example,by UE (e.g., such as a UE 120 in the wireless communication network100).

Operations 1100 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 480 of FIG.4 ). Further, the transmission and reception of signals by the UE inoperations 1100 may be enabled, for example, by one or more antennas(e.g., antennas 452 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the UE may be implemented via a businterface of one or more processors (e.g., processor 480) obtainingand/or outputting signals.

The operations 1100 may begin, at block 1102, by the UE receiving amessage for DAPs HO from a source network entity to a target networkentity, wherein carrier-aggregation (CA) is configured for communicationwith the source network entity prior to reception of the message for theHO. At block 1104, the UE activates a dormancy CA mode with the sourcenetwork entity in response to the reception of the message for HO, andat block 1106, performs the HO from the source network entity to thetarget network entity during a HO period, wherein the dormancy CA modeis maintained with the source network entity during at least a portionof the HO period, and wherein connection with the target network entityis maintained during the at least the portion of the HO period.

FIG. 12 is a flow diagram illustrating example operations 1200 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 1200 may be performed, for example,by a BS (e.g., such as a BS 110 in the wireless communication network100, or the gNB-CU in FIG. 7 ).

Operations 1200 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 440 of FIG.4 ). Further, the transmission and reception of signals by the BS inoperations 1200 may be enabled, for example, by one or more antennas(e.g., antennas 434 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the BS may be implemented via a businterface of one or more processors (e.g., processor 440) obtainingand/or outputting signals.

The operations 1200 may begin, at block 1202, by the BS generating amessage for DAPs HO of a user-equipment (UE) from a source networkentity to a target network entity, wherein carrier-aggregation (CA) isconfigured for communication between the UE and the source networkentity prior to transmission of the message for the HO, wherein themessage indicates to the UE to activate a dormancy CA mode with thesource network entity during at least a portion of a HO period whilemaintaining connection with the target network entity during the atleast the portion of the HO period. At block 1204, the BS transmits themessage to the UE.

FIG. 13 is a timing diagram illustrating a connection mode of a sourcecell (e.g., source network entity) and a target cell (e.g., targetnetwork entity) during MBB HO, in accordance with certain aspects of thepresent disclosure. As illustrated, the connection with the source cellmay be in a dormancy CA mode. In other words, the secondary cell(s)(Scell(s)) (e.g., secondary component carrier(s)) of the source cell maybe in dormancy. In dormancy CA mode, even though the UE is in CA, the UEmay not monitor control signaling (e.g., physical downlink controlchannel (PDCCH)) on the Scell during the DAPs HO. Rather, the UE mayonly monitor PDCCH on the primary cell. By activating dormancy CA mode(as opposed to deactivating CA), the CA activation/deactivation latencymay be reduced without additional burden on the UE to monitor PDCCH onthe Scell(s). For example, in dormancy CA mode, scheduling oftransmissions on the Scell(s) may be performed via the primary cellusing cross-carrier scheduling. CA with dormancy mode may move over tothe target cell after the source cell is released, or a normal CA modemay be configured on the target cell separately. In other words, afterthe connection to the source cell is released (e.g., after step 7 inFIG. 7 ), the UE may configure a CA mode with dormancy with the targetcell, or normal CA for which PDCCH is monitored on both the primary andsecondary cells. In certain aspects, CA may be configured for both thesource cell and the target cell during at least a portion of the HOperiod, allowing the UE to maintain CA with both the target and sourcecells without monitoring secondary cells, reducing the burden on the UE.

FIG. 14 is a flow diagram illustrating example operations 1400 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 1400 may be performed, for example,by UE (e.g., such as a UE 120 in the wireless communication network100).

Operations 1400 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 480 of FIG.4 ). Further, the transmission and reception of signals by the UE inoperations 1400 may be enabled, for example, by one or more antennas(e.g., antennas 452 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the UE may be implemented via a businterface of one or more processors (e.g., processor 480) obtainingand/or outputting signals.

The operations 1400 may begin, at block 1402, by the UE receiving amessage for DAPs HO from a source network entity to a target networkentity, wherein carrier-aggregation (CA) mode is configured forcommunication with the source network entity prior to reception of themessage. At block 1404, the UE performs the HO from the source networkentity to the target network entity during a HO period, wherein the CAmode with the source network entity is maintained during at least aportion of the HO period, and wherein connection with the target networkentity is maintained during the at least the portion the HO period.

FIG. 15 is a flow diagram illustrating example operations 1500 forwireless communication, in accordance with certain aspects of thepresent disclosure. The operations 1500 may be performed, for example,by a BS (e.g., such as a BS 110 in the wireless communication network100, or the gNB-CU in FIG. 7 ).

Operations 1500 may be implemented as software components that areexecuted and run on one or more processors (e.g., processor 440 of FIG.4 ). Further, the transmission and reception of signals by the BS inoperations 1500 may be enabled, for example, by one or more antennas(e.g., antennas 434 of FIG. 4 ). In certain aspects, the transmissionand/or reception of signals by the BS may be implemented via a businterface of one or more processors (e.g., processor 440) obtainingand/or outputting signals.

The operations 1500 may begin, at block 1502, by generating a messagefor DAPs HO of a UE from a source network entity to a target networkentity. CA mode may be configured for communication between the UE andthe source network entity prior to transmission of the message for HO.The message may indicate for the UE to maintain the CA mode with thesource network entity during at least a portion of a HO period whilemaintaining connection with the target network entity during the atleast the portion of the HO period. At block 1504, the BS transmits themessage for HO to the UE.

FIG. 16 is a timing diagram illustrating a connection mode of a sourcecell (e.g., source network entity) and a target cell (e.g., targetnetwork entity) during MBB HO, in accordance with certain aspects of thepresent disclosure. As illustrated, the CA mode on the source and targetcells may be retained during DAPs HO. To support the CA mode on bothsource and target cell during DAPs HO, certain resources may bedistributed between the source and target cells at the UE. UEs withcurrent capability may redistribute resources on both cells by, forexample, reducing the amount of component carriers that are supportedfor CA on each cell. For example, although a maximum of 8 CCs may beallowed on one cell, the 8 CCs limit may be shared across both cells(e.g., 4 CCs on each cell). In some cases, UEs with extendedcapabilities may be able to activate the maximum of 8 CCs per cell. Asdescribed herein, to reduce the UE burden, dormancy CA may be activatedon both cells during the HO period.

FIG. 17 illustrates a communications device 1700 that may includevarious components (e.g., corresponding to means-plus-functioncomponents) configured to perform operations for the techniquesdisclosed herein, such as the operations illustrated in FIGS. 8, 11, 14. The communications device 1700 includes a processing system 1702coupled to a transceiver 1708 (e.g., a transmitter and/or a receiver).The transceiver 1708 is configured to transmit and receive signals forthe communications device 1700 via an antenna 1710, such as the varioussignals as described herein. The processing system 1702 may beconfigured to perform processing functions for the communications device1700, including processing signals received and/or to be transmitted bythe communications device 1700.

The processing system 1702 includes a processor 1704 coupled to acomputer-readable medium/memory 1712 via a bus 1706. In certain aspects,the computer-readable medium/memory 1712 is configured to storeinstructions (e.g., computer-executable code) that when executed by theprocessor 1704, cause the processor 1704 to perform the operationsillustrated in FIGS. 8, 11, 14 , or other operations for performing thevarious techniques discussed herein for DAPS HO. In certain aspects,computer-readable medium/memory 1712 stores code 1714 for receiving;code 1716 for deactivation/activating; and code 1718 for performing HO.In certain aspects, the processor 1704 has circuitry configured toimplement the code stored in the computer-readable medium/memory 1712.The processor 1704 includes circuitry 1720 for receiving; circuitry 1722for deactivation/activating; and circuitry 1724 for performing HO.

FIG. 18 illustrates a communications device 1800 that may includevarious components (e.g., corresponding to means-plus-functioncomponents) configured to perform operations for the techniquesdisclosed herein, such as the operations illustrated in FIGS. 9, 12, 15. The communications device 1800 includes a processing system 1802coupled to a transceiver 1808 (e.g., a transmitter and/or a receiver).The transceiver 1808 is configured to transmit and receive signals forthe communications device 1800 via an antenna 1810, such as the varioussignals as described herein. The processing system 1802 may beconfigured to perform processing functions for the communications device1800, including processing signals received and/or to be transmitted bythe communications device 1800.

The processing system 1802 includes a processor 1804 coupled to acomputer-readable medium/memory 1812 via a bus 1806. In certain aspects,the computer-readable medium/memory 1812 is configured to storeinstructions (e.g., computer-executable code) that when executed by theprocessor 1804, cause the processor 1804 to perform the operationsillustrated in FIGS. 9, 12, 15 , or other operations for performing thevarious techniques discussed herein for DAPS HO. In certain aspects,computer-readable medium/memory 1812 stores code 1814 for generating;and code 1816 for transmitting. In certain aspects, the processor 1804has circuitry configured to implement the code stored in thecomputer-readable medium/memory 1812. The processor 1804 includescircuitry 1818 for generating; and circuitry 1820 for transmitting.

Example Aspects

Aspect 1. A method for wireless communication, comprising: receiving amessage for dual-active-protocol stack (DAPs) handover (HO) from asource network entity to a target network entity, whereincarrier-aggregation (CA) is configured with the source network entityprior to reception of the message for HO; deactivating the CA inresponse to reception of the message for HO to activate a single carriermode with the source network entity; and performing the HO from thesource network entity to the target network entity during a HO period,wherein the single carrier mode is maintained with the source networkentity during at least a portion of the HO period, and whereinconnection with the target network entity is maintained during the atleast the portion of the HO period.

Aspect 2. The method of aspect 1, wherein the message for HO comprisesan indication to deactivate the CA mode with the source network entity.

Aspect 3. The method any one of aspects 1-2, wherein performing the HOcomprises receiving a configuration message indicating to releaseconnection with the source network entity, the HO period including aperiod between the reception of the message for the HO and the receptionof the configuration message.

Aspect 4. The method of any one of aspects 1-3, further comprisingactivating CA with the target network entity after the HO period.

Aspect 5. The method of any one of aspects 1-4, wherein a single carriermode is configured with the target network entity during the HO period.

Aspect 6. The method of any one of aspects 1-5, wherein CA is configuredwith the target network entity during the HO period.

Aspect 7. A method for wireless communication, comprising: receiving amessage for dual-active-protocol stack (DAPs) handover (HO) from asource network entity to a target network entity, whereincarrier-aggregation (CA) mode is configured for communication with thesource network entity prior to reception of the message; and performingthe HO from the source network entity to the target network entityduring a HO period, wherein the CA mode with the source network entityis maintained during at least a portion of the HO period, and whereinconnection with the target network entity is maintained during the atleast the portion of the HO period.

Aspect 8. The method of aspect 7, wherein the CA mode with the sourcenetwork entity is configured with a fewer number of component carriersduring the HO period as compared to the CA mode with the source networkentity configured prior to the HO period.

Aspect 9. The method of any one of aspects 7-8, wherein a CA mode isconfigured with the target network entity during the HO period.

Aspect 10. The method of aspect 9, wherein the CA mode with the targetnetwork entity during the HO period is configured with a fewer number ofCCs than a CA mode activated with the target network entity after the HOperiod.

Aspect 11. The method of any one of aspects 7-10, wherein performing theHO comprises receiving a configuration message indicating to releaseconnection with the source network entity, the HO period including aperiod between the reception of the message for the HO and the receptionof the configuration message.

Aspect 12. A method for wireless communication, comprising: generating amessage for dual-active-protocol stack (DAPs) handover (HO) of auser-equipment (UE) from a source network entity to a target networkentity, wherein carrier-aggregation (CA) is configured for communicationbetween the UE and the source network entity prior to transmission ofthe message for HO, and wherein the message indicates to the UE toactivate a single carrier mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion the HO period; andtransmitting the message for the HO to the UE.

Aspect 13. The method of aspect 12, further comprising transmitting, tothe UE, a configuration message indicating to release connection withthe source network entity, the HO period including a period between thetransmission of the message for HO and the transmission of theconfiguration message.

Aspect 14. The method of any one of aspects 12-13, wherein the messagefor HO comprises an indication to configure a single carrier mode withthe target network entity during the HO period.

Aspect 15. The method of any one of aspects 12-14, wherein the messagefor HO comprises an indication to configure CA with the target networkentity during the HO period.

Aspect 16. A method for wireless communication, comprising: generating amessage for dual-active-protocol stack (DAPs) handover (HO) of auser-equipment (UE) from a source network entity to a target networkentity, wherein carrier-aggregation (CA) mode is configured forcommunication between the UE and the source network entity prior totransmission of the message for HO, and wherein the message indicate forthe UE to maintain the CA mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion of the HO period;and transmitting the message for HO to the UE.

Aspect 17. The method of aspect 16, wherein the message indicate for theUE to maintain the CA mode with the source network entity with a fewernumber of component carriers during the HO period as compared to the CAmode configured prior to the HO period.

Aspect 18. The method of any one of aspects 16-17, wherein the messageindicate to the UE to configure a CA mode with the target network entityduring the HO period.

Aspect 19. The method of aspect 18, wherein the CA mode with the targetnetwork entity during the HO period is configured with a fewer number ofCCs than a CA mode activated with the target network entity after the HOperiod.

Aspect 20. The method of any one of aspects 16-19, further comprisingtransmitting a configuration message indicating to the UE to releaseconnection with the source network entity, the HO period including aperiod between the transmission of the message for HO and thetransmission of the configuration message.

Aspect 21. A method for wireless communication, comprising: receiving amessage for dual-active-protocol stack (DAPs) handover (HO) from asource network entity to a target network entity, whereincarrier-aggregation (CA) is configured for communication with the sourcenetwork entity prior to reception of the message for the HO; activatinga dormancy CA mode with the source network entity in response to thereception of the message for HO; and performing the HO from the sourcenetwork entity to the target network entity during a HO period, whereinthe dormancy CA mode is maintained with the source network entity duringat least a portion of the HO period, and wherein connection with thetarget network entity is maintained during the at least the portion ofthe HO period.

Aspect 22. The method of aspect 21, wherein control information on oneor more secondary component carriers (CCs) are not monitored during thedormancy CA mode.

Aspect 23. The method of any one of aspects 21-22, wherein the messagefor HO comprises an indication to activate the dormancy CA mode with thesource network entity.

Aspect 24. The method of any one of aspects 21-23, wherein a singlecarrier mode of operation is maintained with the target network entityduring the HO period.

Aspect 25. The method of aspect 24, wherein performing the HO comprisesreceiving a configuration message indicating to release connection withthe source network entity, the HO period including a period between thereception of the message for HO and the reception of the configurationmessage.

Aspect 26. The method of any one of aspects 21-25, further comprisingactivating CA with the target network entity after the HO period.

Aspect 27. The method of any one of aspects 21-26, further comprisingactivating a dormancy CA mode with the target network entity after theHO period.

Aspect 28. The method of any one of aspects 21-27, wherein a dormancy CAmode is configured with the target network entity during the HO period.

Aspect 29. A method for wireless communication, comprising: generating amessage for dual-active-protocol stack (DAPs) handover (HO) of auser-equipment (UE) from a source network entity to a target networkentity, wherein carrier-aggregation (CA) is configured for communicationbetween the UE and the source network entity prior to transmission ofthe message for the HO, wherein the message indicates to the UE toactivate a dormancy CA mode with the source network entity during atleast a portion of a HO period while maintaining connection with thetarget network entity during the at least the portion of the HO period;and transmitting the message to the UE.

Aspect 30. The method of aspect 29, wherein control information on oneor more secondary component carriers (CCs) are not monitored by the UEduring the dormancy CA mode.

Aspect 31. The method of any one of aspects 29-30, wherein the messagefor the HO comprises an indication to configure a single carrier mode ofoperation with the target network entity during the HO period.

Aspect 32. The method of any one of aspects 29-31, further comprisingtransmitting a configuration message indicating to the UE to releaseconnection with the source network entity, the HO period including aperiod between the transmission of the message for HO and thetransmission of the configuration message.

Aspect 33. The method of any one of aspects 29-32, wherein the messagefor HO comprises an indication for the UE to activate a dormancy CA modewith the target network entity after the HO period.

Aspect 34. The method of any one of aspects 29-33, wherein the messagefor HO comprises an indication for the UE to activate a dormancy CA modewith the target network entity during the HO period.

The methods disclosed herein comprise one or more steps or actions forachieving the methods. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112(f) unless the element is expressly recited using the phrase“means for” or, in the case of a method claim, the element is recitedusing the phrase “step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userterminal 120 (see FIG. 1 ), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For example, instructions for performing the operationsdescribed herein.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

1. An apparatus for wireless communication at a user equipment (UE),comprising: a memory comprising instructions; and a processor configuredto execute the instructions and cause the apparatus to: receive ahandover message for a dual-active-protocol stack (DAPS) handover (HO)from a source network entity to a target network entity, afterdeactivation or release of a carrier aggregation (CA) mode configuredwith the source network entity; and perform the DAPS HO from the sourcenetwork entity to the target network entity, in response to the handovermessage.
 2. The apparatus of claim 1, wherein the CA mode is configuredwith the target network entity after the DAPS HO.
 3. The apparatus ofclaim 1, wherein the processor is further configured to execute theinstructions and cause the apparatus to receive a configuration messageindicating to release connection with the source network entity.
 4. Theapparatus of claim 1, wherein the processor is further configured toexecute the instructions and cause the apparatus to activate a singlecarrier mode with the source network entity during the DAPS HO.
 5. Theapparatus of claim 1, wherein a single carrier mode is configured withthe target network entity during the DAPS HO.
 6. An apparatus forwireless communication at a source network entity, comprising: a memorycomprising instructions; and a processor configured to execute theinstructions and cause the apparatus to: generate a handover message fora user equipment (UE) for a dual-active-protocol stack (DAPS) handover(HO) from the source network entity to a target network entity;deactivate or release a carrier aggregation (CA) mode configured withthe source network entity; and transmit the handover message to the UE,after the deactivation of the CA mode.
 7. The apparatus of claim 6,wherein the CA mode is configured with the target network entity afterthe DAPS HO.
 8. The apparatus of claim 6, wherein the processor isfurther configured to execute the instructions and cause the apparatusto transmit a configuration message indicating to release connectionwith the source network entity.
 9. The apparatus of claim 6, wherein theprocessor is further configured to execute the instructions and causethe apparatus to activate a single carrier mode during the DAPS HO. 10.The apparatus of claim 6, wherein a single carrier mode is configuredwith the target network entity during the DAPS HO.
 11. A method forwireless communication at a user equipment (UE), comprising: receiving ahandover message for a dual-active-protocol stack (DAPS) handover (HO)from a source network entity to a target network entity, afterdeactivation or release of a carrier aggregation (CA) mode configuredwith the source network entity; and performing the DAPS HO from thesource network entity to the target network entity, in response to thehandover message.
 12. The method of claim 11, wherein the CA mode isconfigured with the target network entity after the DAPS HO.
 13. Themethod of claim 11, further comprising receiving a configuration messageindicating to release connection with the source network entity.
 14. Themethod of claim 11, further comprising activating a single carrier modewith the source network entity during the DAPS HO.
 15. The method ofclaim 11, wherein a single carrier mode is configured with the targetnetwork entity during the DAPS HO.
 16. A method for wirelesscommunication at a source network entity, comprising: generating ahandover message for a user equipment (UE) for a dual-active-protocolstack (DAPS) handover (HO) from the source network entity to a targetnetwork entity; deactivating or releasing a carrier aggregation (CA)mode configured with the source network entity; and transmitting thehandover message to the UE, after the deactivation of the CA mode. 17.The method of claim 16, wherein the CA mode is configured with thetarget network entity after the DAPS HO.
 18. The method of claim 16,further comprising transmitting a configuration message indicating torelease connection with the source network entity.
 19. The method ofclaim 16, further comprising activating a single carrier mode during theDAPS HO.
 20. The method of claim 16, wherein a single carrier mode isconfigured with the target network entity during the DAPS HO.